Fire protective tape

ABSTRACT

A fire protective tape using a halogen-free mastic coating on a fabric support is provided, the essential components of the mastic being solids including a low fusing ceramic frit, hydrated solids having chemically bonded water which is released as a fire protective water vapor when heated, solids which expand or intumesce during the same heat application to form a porous, expanded or foamy insulating body, solids which have a fire break effect, such as antimony oxide and zinc tetraborate, and binder solids which are thermoplastic resins and serve to bind the solids into a flexible coating when applied, the binder solids being dispersed as an emulsion in water and mixed with the other solids to form a mastic. With further addition of water the mastic is converted to a selected viscosity for application by troweling, coating or spraying. The mastic is applied as a coating upon the sheet-like carrier, which may be wound as a tape upon single or grouped electric power and control cables to restrict fire propagation and to prevent self ignition of cables from fires due to overloading or other electrical faults, or from oil, waste or trash fire sources, thereby minimizing the danger of self ignition of gases or combustible materials such as other cable jacketing, insulation or other flammable materials.

This application is a continuation in part of my copending applicationSer. No. 872,820 filed Jan. 27, 1978 and now U.S. Pat. No. 4,189,619issued Feb. 19, 1980 in which the invention relates to a fire protectivemastic and fire stop for electrical cables and neighboring walljunctures or partitions through which the cables pass, the masticcomprising protective water vapor-evolving substances, other substanceswhich intumesce or expand, and still others which glaze with sufficientheat and form a stable protective porous coating having a fused ceramiccasing upon the electric cables and fire stop panels, when exposed tofire. The mastic is also useful as a precast boot for mounting uponcables or splices, or as an air and fire seal or caulk disposed upon orbetween cables, the mastic filling cracks or crevices between cables orpanels and cables, and serves as a coating upon fire stop panels andupon neighboring walls, and for wall paneling per se through whichelectric cables pass as a fire protective wall and in which the panelingor boot per se may be formed of the precast dry mastic.

The invention of the present application relates to an electric arc andfire protective tape, using the mastic of the parent application coatedupon a sheet or strip-like support typically a strip of plastic or ofwoven faber. The mastic contains large quantities such as 60 to 85% of amixture of solids of several types, each with a distinct function toprovide in combination a superior fire protective effect. The solids areformed into a mastic by a binder resin dispersed in water in quantity toform a coherent coating when dry, whereby the solids and the dispersionmay be evenly mixed. Additional quantities of aqueous diluent may beadded in the mixing, for conversion of the dispersion of resins and drysolids to a trowelable, coatable or even sprayable composition, asneeded to provide the requisite fluidity for application.

Some of the solids include intumescing or decrepitating substances,typically cenospheres, which are flyash, inorganic particles evolved asdust from coal combustion and are very light, volatile and expandablewith heat, like tiny fused balloons. It is that expansion of such gasevolving substances in combination with other vapor producing substancesmixed therewith which, when the composition is heated under fireexposure at temperatures above about 1000° F. such as 1200° F. to 3000°F. to activate the intumescing components and release vapors whichconvert the composition from a thin layer coating disclosed in my parentapplication as applied on a cable or panel and herein coated upon acarrier sheet or strip as a tape, to expand to its heat insulating form.Such intumescent solids are present in the range of 5-40%, preferably7-25%.

Other solids present in the mastic composition are of a chemical hydratecharacter, having chemically or physically combined water, such ashydrous oxides, silicates and other hydrated substances which firmlybond the water and which decompose with the heat of a fire and evolvelarge quantities of cooling, non-corrosive oxygen-displacing andfire-protective water vapors. Such hydrous oxides are typically hydrousalumina, magnesia and the other water evolving hydrous oxides andsilicates. These hydrated components are used in quantity of 10 to 40%and preferably in quantity of 15 to 30%.

Still other solids in the mastic comprise a heat fusible ceramic fritwhich, when heated sufficiently upon an outer surface of the expandedcoating, exposed to high fire developed heat, glaze over and encase theexpanded dry mastic as a fire protective film thereon, protecting theexpanded coating and insulating the cables, or in or upon the fire stoppanels or boots. Such frit generally is a low fusible glass, typically aborosilicate glass frit generally fusible in the range of about 700° to1500° F. It is usefully used in the range of about 5 to 40%, andpreferably about 10 to 25%.

The composition includes a thermoplastic resin as a binder dispersed inwater, the aqueous dispersion being mixed evenly with said solids toform the mastic. The thermoplastic resin is present in quantitiessufficient to form a flexible binder for the mastic composition whendry, as a coating upon the electrical cables or panels, or to bind thepanels or boots upon drying into a strong structural form. Sufficientadditional water is added in the mixing as stated, for supplyingrequisite fluidity for application. The resinous solids are present inthe quantity of about 15 to 40% of the dry composition, preferably 20 to30%. Such thermoplastic substances may be any useful thermoplasticbinder resin, which is halogen-free, but which may melt and flow by heatdeveloped during fire and allow the composition to expand to a heatinsulating coating. The typical resins for this purpose are halogen-freeto avoid decomposition and release of noxious and corrosive halogengases, and may be typically polyvinyl acetate, polyacrylic acid,polyacrylic lower alkyl esters, such as methyl or ethyl esters thereof,polymethacrylic acid and its lower alkyl esters, such as methyl andethyl esters thereof, as well as mixtures of such acrylic resins,natural and artificial rubber latices, each as dispersions in water,said dispersions usually having from 25 to 75% of resin solids therein,usually 45 to 65% resin solids, the balance being water with minorquantities of dispersing agents.

The composition may further include small quantities of combustiblefiber, such as cotton, rayon, aramide or the like, to provide atemporary coating stability for the wet or molten mastic. For thispurpose the fiber need not be fire proof and may burn as the compositionbecomes heated when exposed to fire and will only be used in minorquantity, generally less than 5%, usually 0.5 to 2.0% to supply thistemporary binding function. In present use as a coating upon a fibroussheet, the additional fiber may optionally be omitted, with thesheet-like base usually of fiber performing much of this function.

The composition will further contain among the solids, such fireretardant substances as antimony oxides, which develop vapors with heatalong with the protective water vapors evolved. Antimony oxide also is alow fusible component and contributes to the formation of the fused fritcasing during fire exposure. Another fire retardant solid is zinctetraborate which, through synergistic action, further improves thefire-retardant character of antimony oxide in the mixture. These fireretardant antimony oxides and zinc tetraborates are each used inquantity of 2 to 15%, preferably 4 to 10% and 5 to 10% respectively.

Other solids present in the composition are each added for a specificminor function and will be present generally in quantity from about 0.1to 10%, some, generally less than 2%, adequate only to perform thefunction. Thus, other solids may consist of emulsifying agents,typically octyphenyl-polyethoxy ethanol available commercially as TritonX 100, in quantity of about 0.5 to 5%. Rust inhibitors, generally inquantity of about 0.2 to 5%, such as potassium polyphosphoric acidesters. Preservatives, such as fungicides, which are mercury complexes,in quantity of about 0.01 up to about 0.05. Viscosity controllingagents, such as alkali metal salts of polycarboxylic acid or oil basedliquid polysiloxanes in quantity of 0.2 to 5%. Thickeners, such ashydroxy ethyl cellulose and a clay type inorganic gelling agent, such asattapulgite clay in quantity of 0.1 to 2%. These several minor additivecomponents for these functions are used in quantity sufficient for thestated function, and each generally will be present in quantity of lessthan 10%, and usually from 0.2 to 2%.

Thus the vapors evolved are non-corrosive gases consisting of watervapor, antimony oxides and minor heat decomposition vapors of the resinand fiber. Such halogenated resins as release halogen, typicallychlorine, such as polyvinyl chloride or numerous halogenatedplasticizers as also are commonly used in the fire proofing art andwhose destruction and release by heat during cable failure, as byarcing, short circuitry or destruction by fire from other sources in theneighborhood of the cables and protectively coated with such fireproofing substances, as release halogen, are avoided, whereby both themastic composition and carrier sheet upon which the mastic is coated asa tape hereof releases no noxious and corrosive halogen gases.

In forming this mastic mixture, the binder emulsion of resin in water isfurther mixed with the dry intumescing and fire proofing solids, andreduced with a small additional quantity of water as needed tohomogeneously mix the filler solids and emulsion for application.

The mastic can be sprayed in thicknesses of 0.025" to 0.150" and airdried to form a thick flexible coating on the electrical cables and wallpanels forming a heat insulating and fire proofing mastic as well as aneffective heat insulating air seal and fire stop.

The mastic of my parent application is intended both as moldable mixturefor forming into fire proofing boots to be installed upon cable jointsand splices or on dry wall panels through which electrical cables maypass, or as a thick suspension in water to be applicable as a protectivemastic filler and coating body upon and about group cables, enteringleaving and passing through a floor slab or fire wall. Wall penetrationsmay be framed by a laminate-rigid panel board such as pressed ceramicfiber, gypsum, Marinite, having said mastic coating applied and driedupon one or both surfaces thereof, said mastic being poured, troweled orsprayed up to depths of two inches as required.

According to the present invention the mastic is coated upon a sheet orstrip substrate preferably a woven or matted fiber fabric such as apolyester fabric typically DuPont Reemay which is spun-woven polyester.The fabric can also be cotton or a ceramic fiber typically glass fiberor carbonized acrylic fiber, each with characteristic advantages. Forinstance, cotton is almost smokeless, but inorganic fibers are strongerand heat resistant. It is preferred to knife coat the mastic compositionupon the substrate usually fabric, to a selected thickness and dry thecoating thereon at a moderately raised temperature below about 200° F.and preferably between 125° to 190° the temperature being regulated toprevent formation of bubbles by vapors evolving too rapidly. Aconvenient handling is to knife the coating on the fabric as it advanceson rolls through the dryer, the fabric serving as the conveyor andbecoming permanently embedded as a laminate to a dried coated masticthickness of about 0.005 to 0.150 inches preferably 0.010 to 0.045inches.

In prior applications of other heat and fire protective insulationsubstances upon electrical cables including a tape, these according tomy prior U.S. Pat. Nos. 4,018,962 and 4,018,983 included halogenevolving resins and have been loosely wound as tape or mounted as a bootabout a cable joint as fire protective means while or after the cableswere assembled, both the tape and boot being relatively non-coherent tothe cable. It was also proposed in U.S. Pat. No. 3,642,531 and 3,928,210to coat cables as an aqueous emulsion of halogen evolving resins,including essentially halogen evolving plasticizers, the heat insulatingeffect of such coating compositions being largely provided by inorganicfiber which functions comparatively poorly for this purpose, and thehalogen gas evolved with heat decomposition is highly corrosive andtoxic, a source of substantial danger and damage to personnel andequipment. Equally important, such compositions coat poorly and crackupon drying, and, under the destructive effect of high temperature, tendrapidly to peel, flake or powder away from the protective positon uponthe electrical cables which they were intended to protect. Suchcoatings, in contrast to the present fail to adequately meet theimportant fire and heat insulating needs to prevent destruction of cablejacketing and insulation-protecting critical power and multipleconductor control cables and to prevent propagation of fire alonggrouped cables in trays and through wall and floor penetration atflaming temperatures often exceeding 1,900° F.

The invention is further explained with reference to the drawingswherein:

FIG. 1 shows a perspective of groups of mastic covered cables passingthrough a wall which may be protected by the fire stop paneling andmastic hereof;

FIG. 2 is an elevation of several trays of cables arranged in a verticaltier as they will pass through a fire wall protected by the panelinghereof;

FIG. 3 is a detail showing the mastic as an outer lamina layer upon aconventional heat resistant wall board base;

FIG. 4 is a detail showing the mastic poured about cables passingthrough a floor opening;

FIG. 5 shows a section of mastic coated cable;

FIG. 6 illustrates a detail of conduit or pipe sleeve carrying cableswhich is filled with mastic;

FIG. 7 shows the mastic coating hereof on a fabric support; and

FIG. 8 shows the tape hereof wound about an electrical cable;

FIG. 9 shows a composite of several insulated conductors wrapped withthe tape of FIG. 8 prior to the application of an extrudedweatherproofing jacket.

Referring to FIG. 1, a wall 10 of concrete or masonary separates spacesA and B as a partition for normal structural purposes and has arectangular opening 12 cut therein for passage of a tier of trays 14 and16 which support and partially enclose electrical cables 18. Thesecables are conventional groups of power or multiple conductor controlcables mounted, insulated and jacketed for purposes of electricalinsulation and moisture imperviousness. Thus the cables may carrycritical communication circuitry or conduct electrical power, ofttimesof high voltage. In any case, any building construction has many cablesas a valuable part thereof and, for whatever electrical purpose theyserve, great damage can be done to the structure and cables byelectrical faults, such as short circuitry or extraneously caused fire,such as by exposed to flaming combination of oil, trash or the like,developing destructive heat in the cables. Again, the cables themselvesare valuable in terms of the numerous communicating conductors and theredundant circuits which must be provided, as well as importance ofwires which may be a part of the cables per se, all being desirablyprotected. The coating hereof effectively protects cables longitudinallyor vertically against propagation of any fire, regardless of source, sothat fire cannot damage redundant control and power circuits andpenetrate into critical control areas.

Finally, it is desirable not only to encase the cables by firepreventive mastic, but also to protect one side of a partitioning wall10 as a fire stop with insulation and insulating panels formed by thecombination of a fire stop panel and mastic hereof, thus to preventtransfer of heat, flame or evolved gases to the opposite wall side ofthe fire stop.

Electrical cables 18 therefore, and for this purpose, are mounted insupporting trays 44 and 16, which may comprise channel irons 20,connected by a metallic ladder, expanded mesh or solid framework 22which can terminate or pass through the opening 12 of the wall 10. Thelayers of cables can be further supported from below by a heat resistantpanel moulded or cast from the mastic or a knife coated tape or blanketof mastic covered by this invention, the thickness of said blanket beingin the range of 0.050 to 0.200 inches, preferably 0.100 to 0.125 inches.

At the wall opening 12 a further set of wall panels 26, 28 and aremounted each with cut-away portions (not shown) to fit over the cablesand close the wall opening 12, as well as to closely close any spacesbetween cables passing through the wall. The cables pass directlythrough or themselves may each be enclosed in a supporting heatresistant metal sleeve or conduit (not shown). It is sometimes desirableto cover the interstices between the cables with loosely mattedinorganic fiber which forms a filler for large spaces directing andsupporting the mastic to close engagement with the cables and forallowing an overall coating as a bed of cables. Optionally, however, themastic itself may be supplied alone to fill the space between the cablesthrough the entire depth above the lower panel 24 up to a point abovethe surfaces of the cables as shown in FIG. 1, whereby, the cablesbecome fully embedded within the dried mastic. The mastic can be sprayedover the grouped cables as 1/8" minimum thickness coating.

Moreover, the mastic 30 is extended to cover the paneling 26,28 and tofill all of the cracks and crevices therein, whereby the cables passthrough the paneling and through the opening 12 of the wall 10, eachcrack, opening or space being filled with mastic. It may also be appliedwithin conduit carrying cables to fill or plug the same as shown in FIG.6. Moreover, the mastic is applied over the top of the cables and forsecure closure of any cracks between panels, both around the panel edgesas well as any spacing or cracks between the adjacent panels.

As shown in FIG. 1 two trays of cables pass through the wall 10 with theconstruction described. The cables may be present in any number andarranged in the trays in any grouping. Additional cables may be passedthrough the wall of the construction by cutting through the lightpre-cast panels, cutting away some of the mastic and penetrating throughthe panel in a circular cut in a manner to accommodate one or moreadditional cables to be added from time to time, and the new cable beingreadily thrust through a newly formed cut portion. The newly addedcables are coated with more fresh mastic and any cracks or crevicesremaining about the newly added cables in the panels are further coatedand sealed with more mastic, whereby additional cables are easily addedfrom time to time.

As shown in FIG. 2, many trays can be assembled in a tier of trayspassing to or through the wall, depending upon the wall size accordingto the size and height needed above the floor 32, whereby two stacks ormore trays as may be needed to accommodate all of the cables can beused. In that case the separate stacks of cables C and D may be furtherseparated by a partitioning wall 34, in which larger panels of themastic hereof are assembled as a separating partition 34 and thepartition may be supported as shown by angle iron brackets 36. It may beuseful to separate the panels by a central laminated layer 38 which maybe of metal wire or glass fiber or other reinforcing material.

The fire stop wall may be formed of fire proof paneling material,resistant to heat, whereby to operate as a fire-protective shield orpartition between the opposite wall sides of spaces, as an easilyassembled fire stop partition through which a group of cables pass,whereby the protective wall prevents heat and flame transfer, as well asthe transfer of noxious vapors or smoke to its opposite wall side wherecontinuing or redundant circuits may be installed. Particularly, thefire stop wall is intended to prevent transfer of heat, to the wall sideopposite to that facing fire exposure and remains relatively cool on theopposite wall side from the high temperatures that may develop from acable failure. The paneling may be formed of other useful pre-cast fireproof materials, but often is of the same dried mastic material as themastic, also being applied as a coating upon the cables hereof, themastic being cast into panels for assembly as dried panels into the firestop wall hereof.

FIG. 3 illustrates a panel board which can be of any commercial ceramicfiber rigid insulating board (41) and which has coated thereon a thin1/8 to 1/4" coating 42 of the mastic hereof.

As shown in FIG. 4 cables disposed as groups or individual cablesdisposed as groups or individual cables in sleeves pass through a floorslab 10 within the mastic hereof poured about and with the sleeve toform an air seal as well as a fire stop. FIG. 5 shows a section of asingle coated cable with mastic applied by spraying, hand-wiping orextrusion.

Particularly for the present invention, the tape hereof is superior forwrapping of cables and electrical splices in that the mastic is moreeasily wrapped thereabout in the conventional application as a tape andsuperior in that the mastic does not evolve halogen vapors at or abovedecomposition temperatures. It is outstanding for protection ofpersonnel and corrodable equipment exposed in confined spaces under hightemperatures resulting from short circuiting conditions or other firesource, such as in mines, subways, shipboard, buildings and otherconfined spaces in which electrical equipment is placed or passesthrough, by virtue of the fact that no halogen is evolved atdecomposition temperatures.

The present composition is highly heat and fire protective. It evolvesonly non-corrosive vapors, such as water vapors, inert nitrogen and CO₂gases, antimony oxides and zinc tetraborate. It produces a porous heatexpanded heat insulating body protective of the cable when destructiveheat is applied, the coating being developed by expansion of theintumenscent substances and evolving gases which convert the coating toan expanded, porous, heat insulating body. The coating further containsa heat fusible frit which forms a glaze, strengthening and protectingthe coating despite very high temperatures, whereby the coating is lowheat transferring and does not powder, flake or peel off the surface ofthe cable to which it was applied.

Theoretically, it appears that during the heating process when ignitionand combustion take place through electrical faults such as arcing orshort circuitry or other source of high heat evolution, the coatingfirst in the presence of heat softens the thermoplastic component. Theintumescing substances such as cenospheres and the hydrous oxides withenough heat begin to expand as well as to evolve water vapor as well asnitrogen and CO₂ gases which are occluded in the cenospheres. Theantimony oxide at higher temperatures can evolve its vapors. The fiberwhich is ultimately heat decomposable, operates in the cold to help bondthe composition into a firm, strong and crack-free coating while itdries. As the initial heating is applied, the thermonplastic bindermelts, but the fiber tends to prevent the resin from flowing away,maintaining the integrity of the composition while it steadily expandswith the heat. Ultimately the fiber and the resin may be charred to aninfusible porous mass, developed by the expanding intumescing solids.The expanding mass carries much of the fusible frit to the coatingsurface, where at high heat exposute temperatures, the frit can fuseprotectively as a refraction shell over the porous mass to preventfurther heat passing into or from central or inner cable portions. Theglazed frit serving further as a reinforcing shell to prevent furtheringress of great heat and prevents the mass from peeling or flaking awayfrom its protective position about the cable.

The composition functions similarly either as a component of the totalpanel body or as an even outer layer on the paneling, whereby the masticsubstance thereof will expand with heat protectively as a fire barrieror stop. One side of the panel of great heat exposure absorbs andprevents passage of heat, acting as a heat and fire stop partition orprotective wall, allowing little heat to pass to the opposite side whichremains comparatively cool. A similar effect is achieved both by usingordinary non-heat conductive paneling substances such as commerciallyavailable insulating board of ceramic fiber which, however, is coatedwith the mastic hereof to improve the wall paneling as a fire stopthrough which the cables pass.

The water component hereof is free water. The resinous emulsion may bequite thick and more water to that contained in the resinous emulsion isusually added merely supplied as free water in quantity sufficient toadjust the mixture to a trowelable, pourable, on down to sprayablemastic, as desired. For purposes of easy distribution of the water,various surfactants such as Triton X 100 an alkylphenoxy,polyloweralkyleneoxy, loweralkanol in which the alkyl has 1-2 carbonatoms, and the product may contain from about 10-40 alkyleneoxy groups.

The resinous binder hereof is dispersed as an emulsion in water inconcentration of 45 to 65% resin solids the remainder being water. Minoradditives may be supplied to improve the body and flexibility, typicallyan anti-foam agent such as Colloid 677, an oil based polysiloxane,thickeners such as hydroxylethyl cellulose, rust inhibitors such asStrodex PK-90, a potassium polyphosphoric acid ester, and preservativesof an anti-fungal nature, such as Troysan, an organic mercurial complex.Such additives will be used in the minor quantity 0.1 to 5% andsometimes as high as 10%, but generally less than 1%, and usefully lessthan 0.2% such as 0.1 to 1%, and are generally mixed in a carrier suchas a propylene glycol in quantity usually less than 2%, such as 0.5-1%.

    __________________________________________________________________________    THE FOLLOWING IS A GENERAL FORMULA FOR THE MASTIC                                                     WEIGHT PERCENT                                                                           TOTAL                                                              PREFERRED  RANGE                                      __________________________________________________________________________    WATER (added to control body)                                                                         5-15       1-30                                       RESINOUS DISPERSION                                                           Halogen-free resin solids                                                                             20-30      15-40                                      ADDITIVES                                                                     Common surfactant, e.e. Triton X 100, octyl                                                           0.2-5      0.1-10                                     phenyl polyethyleneoxyethanol, Tamol sodium                                   polycarboxylate; Anti-foaming agent, i.e.                                     colloid, oil based polysiloxane; thickener,                                   QP 4400 hydroxy ethyl cellulose; Strodex PK                                   90, potassium polyphosphoric acid methyl ester;                               attapulgite gel, diatomaceous clay; fungicidal                                preservative, Troysan CMP acetate mercurial                                   complex, propylene glycol, or wet strength                                    enhancing acrylic resin                                                       ORGANIC FIBER                                                                 Typically aramid, rayon, wool or cotton.                                                              0.5-2.0    0.1-5                                      WATER VAPOR EVOLVING                                                          Hydrous oxides (inorganic hydrates having                                                             15-30      10-40                                      chemically combined water evolvable only                                      under fire conditions).                                                       INTUMESCENTS                                                                  Cenospheres             7-25       5-40                                       FIRE-PREVENTATIVES                                                            Zinc Tetraborate        5-10       2-15                                       Antimony Oxide          4-10       2-15                                       FRIT                                                                          Ceramic Glazing Solids (typically low-fusing                                                          10-25      5-40                                       borosilicate glasses generally calcium, magnesium,                            zirconium, borosilicates (generally lead-free)                                __________________________________________________________________________

In forming the composition, the dry components are mixed and evenlyblended with the plastic to form a heavy mastic, adding a small quantityof water in the range stated, sufficient to bring the mastic up toviscosity suitable for application upon the cables assembled and panelsas show, filling all of the openings, cracks and crevices. The masticformed as described may be extruded or pressed into sheets of desiredthickness, such as 1/4-11/2 inches thick. In order to improve both thedry and wet structural properties of the panel pressed or extruded fromthe mastic mass, an addition of a heat polymerizable acrylic resin, suchas Rohm and Haas X-980 is added. The wet panel may be set by drying andremoving the moisture at ambient temperatures. When the acrylic additivein the range of 2-10%, preferably in the range of 4-6%, it is necessaryto raise the panel temperature to 300°-350° F. in order to complete thepolymerization. Without such acrylic additive, the tape or other masticproduct is less sensitive to moisture.

The cables themselves are encased in coating, which may be thin andflexible or may be applied as a filler mastic between a group of cablesas shown in FIG. 1 and which may pass through the paneling, cut withholes to allow cables or trays having a number of separately spacedcables to pass through from side to side of the fire stop wall, and thecracks and crevices about each cable are then filled with the mastic asshown in FIGS. 1 and 6. Thus the mastic is applied by spraying,troweling or brushing upon the cables, between the cables, upon the firestop wall as a coating and as the paneling substance from which the wallper se is formed.

As shown in FIG. 7 an electrical arc and fire protective tape isprovided having cellulose sheeting or non-woven polyester film or fabricbase 102 or preferably cellulose fibers such as cotton or rayon whichhave been previously treated with fire retardant salts and, on thissubstrate a coating 104 of the mastic described above is appliedpreferably within the thickness limits stated. The mastic can also havesmall fibers 106 as listed above embedded within the mastic. In formingthe tape, the fabric 102 becomes a conveyor and the wet mastic isapplied in the thickness within the range stated by a knife and doctorblade as in conventional coating, the wet coated sheet is passed througha warmed oven or drying chamber through which a stream of warm air iscirculated to provide a drying temperature lower than about the boilingpoint of water, whereby the water will evaporate to leave the driedmastic coating upon the fabric. It is desirable to dry the coated sheetor fabric in the warm air stream while moving at low speeds of below 10feet per minute, a rate slow enough within the drying chamber to allowremoval of the moisture from the tape at a slow enough rate to avoid anysignificant formation of vapor bubbles in the wet mastic while drying.That drying rate can be accelerated somewhat by inclusion of a smallquantity of mineral spirits such as petroleum about 1 to 2% added to themastic mixture, to supply an azeotropic vaporization of the water andpetroleum ether at a somewhat lower temperature and thereby promote afaster drying rate. The azeotropic component can be omitted and thedrying can be effected at a slower rate. The tape having dry masticthereon bears the benefits of the superior fire and arcing preventioncharacter of the mastic.

As shown in FIG. 8 the tape 100 may be wound about a cable sheath 108 inthe manner typical for the insulation of a cable by a tape. As shown inFIG. 9 the tape 100, which in this case is a thin laminate of mylar(0.001") 103 and mastic (0.010") 100 wrapped around the insulatedmultiple conductors and the mastic/mylar laminate wrap covered with anextruded water resistant jacket 108 of polyethylene, polypropylene,ethylene propylene rubber or equivalent of some 30 mils thickness.

As noted the tape support or substrate 102 may be of various types ofwoven or matted fiber, of which Reemay, a polyester spun-woven fabric isoften preferred because of its substantial strength. It bears thedisadvantage, however, that it evolves smoke with heat decomposition andfrom that aspect ordinary very light rayon or cotton fabric, such asgauze or even cheesecloth made fire retardant by pretreatments can beused because these evolve little smoke and will serve to adequatelysupport the mastic layer while it is being applied as a knife coatedsurface layer. As a tape cotton fabric is physically of weakerconstruction but has the stated advantage of giving off little smokeupon heat decomposition. Polyester film such as Mylar as thin as statedcan be used as a substrate in tapes for cable manufacturing. Also,ceramic fiber fabric or sheet can be used advantageously in that theygive off no smoke and are more heat resistant, but from the aspect ofeconomy are more expensive.

The following examples illustrate the practice of this invention:

EXAMPLE 1

Four hundred and sixty-two pounds of vinyl acrylic polymer dispersed inwater in quantity of about 277 lbs of polymer, the remainder of saidemulsion being water and additives. The additives consist of 13 lbs ofpropylene glycol, 6 lbs of Colloid 677, oil based liquid polysiloxane,1.5 lbs. of hydroxy methyl cellulose, 6.5 lbs of rayon fiber, 1.5 lbs ofStrodex PK 90, potassium polyphosphoric acid ethyl ester and 0.5 lbs ofa mercurial complex preservative. The entire mixture being a viscousdispersion in water. Separately, a dispersion of 1.0 lbs of Triton X100, which is octyl phenyl polyethyleneoxyethanol, 5.7 lbs of Tamol,sodium salt of polycarboxylic acid, are dispersed in 50 lbs of water.The aqueous solution of dispersing agents and additives is used todilute the first resinous emulsion. Thereafter dry powders consisting of190 lbs of hydrous aluminum oxide, 90 lbs of cenospheres, 80 lbs of zinctetraborate, 68 lbs of antimony oxide and 163 lbs of frit, a lowtemperature borosilicate glass essentially lead-free calcium silicateceramic glass, available from the Ferro Corporation as FB282. Thickenerssuch as Attagel 40 are added to the extent of 10 lbs to controlconsistency. The dried powders are mixed into the diluted liquidemulsion to form a sprayable mastic which is sprayed upon electricalcables and upon fire stop panels. The mastic dries at ambienttemperatures in air to form approximately a 1/8 to 1/4 inch thick, onaverage, coating, firmly and flexibly adherent to the cable surface. Thebase of the panel is commercial ceramic fiber board, such as Kaowool,Duraborad board of 1 inch thickness.

The coated panel of example I, about 1" inch was tested according toASTME 119 by supporting the panel above a flame having an average firingtemperature of 1725° F. The flame impinges against the coated side andthe temperature of the uncoated side was measured to determine the heattransfer effect. It was found in a series of three hour burning teststhat the maximum temperature measured on the uncoated side was about330° F. for the board with a 1/4" coating the heated mastic generatedonly a small amount of smoke, the coating remained well adherent to theinsulating board. For a 1/8" thick coating with mastic the averagetransferred temperature was 350° F. In a comparison with a competitivecomposition the temperature for a 1/8" coating was 380° F., and for anuncoated board the temperature was 400° F. In separate tests it wasfound that a standard vertical burn test (IEE - 383) applied to groupedcables coated with this mastic was self extinguishing after removal ofthe flame source; there was no apparent damage to jacketing orinsulation during a 20 minute burn in which about 70,000 BTU per hourwas applied to the coated cables, and there was no flame propagationafter removal of the burner. The coating of this example is flexible,and after drying, the coated cables can be bent without cracking of thecoating.

EXAMPLE 2

A similar mastic as example 1 was formed using a commercial mixture ofpolyacrylate resins dispersed in water available as UCAR 163, havingsimilarly about 60% of polyacrylate total solids, of which 58% was mixedpolyacrylics, the remainder being additives as in example 1. This thickresin was similarly diluted with water and additives, thinning the thickemulsion and into which is added the powders as example 1. The masticcoated upon the cables as shown is flexible and fire resistant by thesame tests, and is highly heat insulating, a 1" thick panel coated withthe mastic to a thickness of 1/8 average, and similarly exposed to a1725° F. exposed flame for a three hour time period, transferred theaverage temperature to the opposite side of about 345° F. over the testperiod. Seven conductor control cables coated with a thickness of 1/8"min. were still flexible, and, in a special Factory Mutual test, wereimmersed and cycled in and out of 60° C. 1% salt water solution forthirty days, and the coating was unaffected and remained firmlyadherent. In each of the tests examples 1 and 2 the heated surface had aceramic glaze and the coating had expanded to a porous film of abouttwice the original applied and dried film thickness.

EXAMPLE 3

The mastic of Example 3 was formed by similarly thinning the commercialresinous dispersion of polyacrylic resins, reducing the extra quantityof water used in the thinning to a maximum of 15 lbs., whereby, themastic was thicker and trowelable. In order to enhance the physicalproperties, particularly the wet modulus of the panels heat polymerizedarcylic resin is added in the range of 2-10%, preferable 4-6%. In thisform it was cast into panels and used as a fire stop panel in a test byexposure to a 1700°-1750° F. flame. The maximum temperature on the coolside a 1" panel was 285° F. on average over a three hour test period,the panel expanding and charring in the area of the applied heat, butconducted no flame when the burner was withdrawn.

As shown in FIG. 4 one or more cables can be passed vertically through amasonry floor, for which purpose they may be mounted within a pre-formedsleeve and the mastic poured around the sleeve. The mastic may also, asshown in FIG. 6 be filled into the body of the sleeve or applied only inseparated portions thereof for support, thus acting as a firestop andsealing the cables for prevention of gas flow between spaces separatedby the floor. The mastic will be filled or applied around the outside ofthe sleeve as shown to selected depth, and other fire stop paneling asshown in FIG. 1 may also be used to close the floor opening.

FIG. 5 shows a single cable having a dried precoated film of masticthereon, a form in which the cable itself may be handled.

EXAMPLE 4

The mastic composition as set forth in Example 1 is wet coated by doctorblade upon a strip of spun-woven Reemay fiber, a commercial productavailable commercially from the duPont Company, in a thickness of 0.035inches and passed through an air drying oven slowly at about 1.5-5linear feet per minute while being warmed by a counter current flow ofair at 180° F. being substantially dried, cooled in air, slit intoappropriate widths and wound into a roll of tape. That roll of tape waswound upon a cable, the cable was wound in 1/2 overlap per turn about11/2 inch lead sheathed cable, as shown in FIG. 8, and heated to atemperature between 1700° and 1750° F. by a Fischer burner.

    __________________________________________________________________________    The tape formed has the following characteristics:                                                SUPERIOR FIRE PROTECTION                                  CHARACTERISTICS     DERIVED FROM:                                             __________________________________________________________________________    Length of roll - 25' to give                                                                      a. Chemically bound water                                 great economy in shipping,                                                                        in mastic composition driven                              handling.           off during fire exposure to                               Weight per 3" × 25' roll - 28 ozs.                                                          provide cooling and reduce                                                    oxygen.                                                   Thickness - 0.045"  b. Inert gases (CO.sub.2, N.sub.2)                        Tensile strength - 350 psi (ASTM D-100)                                                           physically entrapped in millions                          Elongation - 125% at break                                                                        of hollow spheres (cenospheres)                                               released during fire to displace                                              oxygen needed to support combustion.                      Color - grey c. Formation of a refractory.                                                        heat reflective surface over                              Resistant to fresh and salt water.                                                                the burned area.                                          sewage, acids, radiation.                                                     Flexible and conformable.                                                                         d. Mild intumescence providing                                                additional heat insulation.                               Fumes from combustion - noncorrosive                                          with minimal health hazard. Cellulose                                         based substrate gives low smoke level.                                        Burn - through resistance - prevents                                          1700° F. flame from burning through                                    and melting lead (625° F.) for                                         periods in excess of 30 minutes.                                              __________________________________________________________________________

The following table compares the results with several other commercialfire protective tapes offered in the trade for electrical similarpurposes:

    __________________________________________________________________________                                        E. U.S. Pat.                                                                              F. Example 4                  TAPE:   A     B        C      D     No. 4018962 Example                                                                       above                         __________________________________________________________________________    CURVE:                                                                        SUBSTRATE:                                                                            Carbonized                                                                          Glass Skrim                                                                            Polyester                                                                            Nylon Spunwoven   Cotton Gauze                          Organic                                                                             Fabric Embedd-                                                                         Spunwoven                                                                            Woven Polyester   Fabric                                Fabric                                                                              ed between PVC                                                                         Fabric Skrim Fabric                                                  Film            Fabric                                          ELASTOMER:                                                                            PVC   PVC Calendered                                                                         PVC Calen-                                                                           Neoprene                                                                            PVC Plastisol                                                                             Mastic water-based                    Coating                                                                             Film     dered Film                                                                           Calendered        Example above.                                              Film Lam-                                                                     inate                                           COLOR:  Black White    White  Brown Gray        Gray                          THICKNESS:                                                                            0.065"                                                                              0.053"   0.050" 0.047"                                                                              0.055"      0.045"                        TIME: (mins.)                                                                         TEMP °F.                                                                     TEMP °F.                                                                        TEMP °F.                                                                      TEMP °F.                                                                     TEMP °F.                                                                           TEMP °F.                1/2    165°                                                                         140°                                                                            100°                                                                          200°                                                                         100°                                1      340°    290°                                                                          330°                                                                         260° 200°                    2      380°                                                                         308°                                                                            500°                                                                          500°                                                                         375° 290°                    3      550°                                                                         412°                                                                            640°                                                                          610°                                                                         410° 385°                    4      625°                                                                         500°     650°                                                                         435° 437°                    5            624°           470° 472°                    6                                  515° 500°                    8                                  565° 537°                    9                                  600°                               12                                              582°                   14                                              595°                   16                                              609°                   18                                              615°                   __________________________________________________________________________

It will be noted from the data on this table that various commercialtapes listed as A, B, C and D have poor insulating effects to destroy itat high temperature and temperatures of 625° F.±25° which is the meltingpoint of a lead sheath were reached in times of four minutes or less,whereas the tape E of U.S. Pat. No. 4,018,962 had a much superior fireresistance but chlorine fumes resulted from the PVC combustion. The tapeF of this invention, besides having even superior fire resistance, ishalogen free.

The tape hereof can be applied protectively about other electricalequipment, cables, cable splices and appurtenant equipment for fire andelectrical arcing protection.

.Iadd.While the invention has been described herein in the preferredform as a tape, it should be appreciated that, as indicated hereinabove,the mastic may be used in other applications, such as, for example, onpanels or fire stops. Such a mastic may be formed in accordance with thegeneral formula set forth hereinabove with the fire protective solidseliminated, the remaining elements being within the ranges specified inthe formula. .Iaddend.

Various modifications will occur to those skilled in the art,particularly other hydrous oxides and other known ceramic frits may besubstituted.

Accordingly, it is intended that the disclosure be regarded as exemplaryand not limiting, except as defined in the claims.

I claim:
 1. An electrical arc and fire protective tape for dispositionabout electrical equipment, cables, cable splices, appurtenant equipmentor the like, comprising a resinous mixture coated as a wet masticmixture and dried upon a fabric base or plastic sheet or film substrate,said mastic comprising an essentially halogen-free mixture of solids andthermoplastic binder resins dispersed as an emulsion in water, saidsolids including heat intumescing and expanding substances inapproximate quantity of 4 to 25% to expand the mastic to porous heatinsulating foam, ceramic frits in approximate quantity of 5 to 40% toprovide a ceramic glaze upon the surface of the dry expanded mastic whenexposed to high temperatures developed by fire, hydrated substances inapproximate quantity of 10 to 40% and having bonded water evolvable onlyby application of sufficient heat to decompose and evolve water vapors,and a resinous thermoplastic binder in approximate quantity of 5 to 40%to bind said solids to the form of a flexible film in coated form of themastic, said binder being dispersed as an emulsion in water, there beingsufficient water in the emulsion to convert said solids into a fluidizedform for application as a coating upon said base or substrate, saidpercentages being by weight, the said solids quantity being based on thetotal solids of the composition.
 2. The tape as defined in claim 1, saidmastic further containing a small quantity, less than about 5% oforganic fiber said composition further containing from about 1 to 10% ofemulsifying agents, rust inhibitors, fungicides, viscosity controlling,thickening, and wet strength enhancing agents.
 3. The tape as defined inclaim 1, wherein the binder resin solids are in the range of 20 to 30%,dispersed in water, being substantially 45 to 65% resin solids and 55 to35% water, the low fusible solids are ceramic frits in quantity of 10 to25%, the hydrated substances are hydrous oxides in the ranges of 15 to30%, the intumescing and expanding substances are cenospheres in therange of 7-25%, said mastic further containing a small quantity of about0.5 to 2.0% of organic fiber.[., and fire retardants antimony oxide andzinc tetraborate, each present in quantity of 4 to 10% and 5 to 10%respectively.]..
 4. The electrical arc and fire protective tape asdefined in claim 1, wherein the fabric base is organic fiber in woven,knitted, netted or non-woven matted form.
 5. The electrical arc and fireprotective tape as defined in claim 1, wherein the fabric base ispolyester fiber in woven, knitted, netted or non-woven form.
 6. Theelectrical arc and fire protective tape as defined in claim 1, whereinthe fabric base is formed of carbonized acrylic fiber in woven, knitted,netted or matted form.
 7. The electrical arc and fire protective tape asdefined in claim 1, wherein substrate is a cellulose or polyester filmsuch as cellophane or mylar in the thickness range of 0.001 to 0.005".8. The electrical arc and fire protective tape as defined in claim 1,wherein the coating has a thickness in the range of 0.005 to 0.150inches.
 9. The electrical arc and fire protective tape as defined inclaim 1, wherein the heat intumescing substances are cenospheres. .[.10.The electrical arc and fire protective tape as defined in claim 1further including about 2 to 15% of protective solids of the characterof antimony oxide and zinc borate..].
 11. The electrical arc and fireprotective tape as defined in claim 1, wherein the fabric base is formedof inorganic fiber in woven, knitted netted or matted form.
 12. Theelectrical arc and fire protective tape as defined in claim 1, whereinthe fabric base is formed of glass fiber in woven, knitted, netted ormatted form. .Iadd.13. A fire retardant mastic comprising an essentiallyhalogen-free mixture of solids and thermoplastic binder resins dispersedas an emulsion in water, said solids including heat intumescing andexpanding substances in approximate quantity of 4 to 25% to expand themastic to porous heat insulating foam, ceramic frits in approximatequantity of 5 to 40% to provide a ceramic glaze upon the surface of thedry expanded mastic when exposed to high temperatures developed by fire,hydrated substances in approximate quantity of 10 to 40% and havingbonded water evolvable only by application of sufficient heat todecompose and evolve water vapors, and a resinous thermoplastic binderin approximate quantity of 5 to 40% to bind said solids together, saidbinder being dispersed as an emulsion in water, there being sufficientwater in the emulsion to convert said solids into a fluidized masticform, said percentages being by weight, the said solids quantity beingbased on the total solids of the composition..Iaddend. .Iadd.14. Thefire retardant mastic as defined in claim 13, wherein the heatintumescing and expanding substances comprise cenospheres..Iaddend..Iadd.15. A fire retardant mastic comprising an essentially halogen-freemixture of solids and thermoplastic binder resins dispersed as anemulsion in water, said solids consisting essentially of: intumescingand expanding substances to expand the mastic to porous heat insulatingfoam, ceramic frits to provide a ceramic glaze upon the surface of thedry expanded mastic when exposed to high temperatures developed by fire,hydrated substances having bonded water evolvable only by application ofsufficient heat to decompose and evolve water vapors, and a resinousthermoplastic binder to bind said solids together, said binder beingdispersed as an emulsion in water, there being sufficient water in theemulsion to convert said solids into a fluidized mastic form..Iaddend.